The present invention relates to a reactor building incorporating a device ensuring the positioning of internal structures, whilst permitting the free thermal expansion thereof.
The building in which a nuclear reactor is installed, called a reactor building, is constituted by a confinement enclosure within which are arranged the internal structures, which support the components of the primary circuits. These structures essentially comprise a floor, called the internal structure floor, a structure called a vessel shaft surrounding and supporting the reactor vessel and hot cells arranged around the vessel shaft. The confinement enclosure prevents any leakage of radioactive substance in the case of an incident and resists the pressure and thermal stresses resulting from a possible fracture to the primary or secondary circuits. The confinement enclosure is constituted by a floor, called the general floor, a cylindrical skirt on the general floor and a dome sealing the upper part of the cylindrical skirt. The confinement enclosure is sealed by a soft steel covering, called a skin.
In the case of an earthquake, it is necessary to prevent any horizontal displacement between the floor of the internal structures and the general floor. It is also advantageous to permit the free expansion of the internal structures from the vessel shaft and relative to the confinement enclosure.
Reactor buildings are known in which the internal structures are locked relative to the general floor by clamping the base of the vessel shaft by means of mechanical stops. The latter are anchored in a concrete slab resting on the general floor. The concrete slab has a recess in the central part of its lower face. A circular boss having a complementary shape made in the general floor engages in the concrete slab recess. Thus, the slab is locked relative to the general floor and consequently the vessel shaft and internal structures are locked relative to the general floor. The confinement enclosure is sealed by a soft steel covering. The latter follows the displacement of the boss formed in the general floor. This system has a complicated construction and also makes it more difficult to produce the tight covering.